final dental presentation

8/13/2019 Final Dental Presentation

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Tooth Decay and

Stuff


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Tooth Decay

Tooth decay has been present sincethere have been teeth to decay.

Tooth decay, is an infectious disease thatdamages the structures of teeth

Pain

Tooth LossInfection

Death


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The Chemistry

Tooth decay is

Acid/Base

chemistryAcids dissolve the

enamel surface of

the tooth and

create holes in thetooth (cavities)


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What is Enamel?

Calcium hydroxyphosphate,Ca5(PO4)3OH, also known as mineral

apatiteAcid attacks apatite:Ca5(PO4)3OH(s) (Tooth enamel) + H

+(Acid) (aq)

Ca5(PO4)3+

(aq) + H2O(l)

Reaction is reversible: saliva


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Fluoride is your friend

If fluoride, F-, ions are present in saliva,fluorapatite, Ca5(PO4)3F, also forms.

Ca5(PO4)3+(aq) + F-(aq) Ca5(PO4)3F (s)

Fluorapatite better than apatite itself(fluoride treatments)


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Tooth decay, not just candy

anymoreNot bacterial growth in the mouth,

but alterations in internal body

chemistryBut candy doesnt help!


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What is a Dental Filling?

Dental material used to restore the

function/integrity/morphology of

missing tooth structure

-Indirect and direct restoration

-Numerous types of methods


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Amalgams?

An amalgam is a mixture of mercury withanother metal or alloy.

Most metals are soluble in mercury.

Amalgams are commonly used in dentalfillings.

Dental amalgam consists of three solid phasesrepresented by Ag2Hg3, Ag3Sn, Sn8Hg


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Dental Amalgams

Dental amalgam is a stable alloy made bycombining elemental mercury, silver, tin,copper and possibly other metallic elements.

~65% minimum, silver copper

~6% maximum, copper

~2% minimum, zinc~25% maximum, tin

~45% liquid mercury


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Why Dental Amalgams?

-Amalgams withstand chewing loads

-Useful for restoring molars in the back ofthe mouth

-They are well tolerated by patients, rareoccurrences of allergic response.


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Why Mercury?

Nearly every metal is soluble in mercury, iron is the onlyexception

Thus, a malleable paste before solidification can beformed

As silver dissolves, flexible but firm structure is molded

Adheres to tooth enamel

Forms high-strength compound


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Primary controversy

Opponents of dental amalgams with mercuryargue the long-term effects of mercurypoisoning

Combination of metals should be safe

Some action taken before to ban mercury fillings

internationally, but FDA, USPHS, CDC-approved

Not enough research to fully support either side


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Controversy


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Battery in your mouth?

Try this at home!: Aluminum foil pressing againstamalgam filling will cause pain

An electrochemical cell is created whenaluminum foil contacts a dental amalgam.Aluminum contacts Sn8Hg phase

Aluminum becomes the anode and the filling as the

cathode.

Saliva acts as an electrolyte.

The contact between the metals acts as a short-circuit


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Dental Filling Corrosion

Dental filling can corrode over time

Different metals can create anelectrical circuit, such as gold andsilver.


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Electricity in Your mouth

Silver and Gold have 3 different solidphases (volt potential):

Ag2Hg3 (0.85 v)Ag3Sn (-0.05 v)

Sn8Hg (-0.13)

Experiments you can do at home tocreate your very own circuit


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Experiments

No, not that if

you have a filling

or braces trychewing on

aluminum foil.


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The Corrosion

Sn8Hg --> Sn2++ 2e-

O2(g) + 4H+(aq) + 4e---> 2H2O (l)


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Grills Arent Dental Fillings!


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Sourceshttp://www.ada.org/public/topics/fillings.asp#restoring

http://en.wikipedia.org/wiki/Amalgam

Chang, Raymond. Chemistry; McGraw-Hill: San Francisco,2002.

http://en.wikipedia.org/wiki/Dental_fillings#Restoration_classifica

tionshttp://en.wikipedia.org/wiki/Dental_amalgam_controversy

http://www.madsci.org/posts/archives/oct2000/973002607.Ch.r.html

http://adr.iadrjournals.org/cgi/reprint/2/1/71.pdf

http://www.mercurypoisoned.com/dentists_disciplined/ImageDe

ntistNewsletter.jpghttp://lonestartimes.com/images/Weidenhof/grill.jpg

http://www.seemygrill.com/f/pics/114744405718814-

phpr0RvoL.jpghttp://farm1.static.flickr.com/35/72218577_035bb

4c2b5.jpg

http://farm1.static.flickr.com/35/72218577 035bb4c2b5.jpg
http://en.wikipedia.org/wiki/Dental_fillingshttp://en.wikipedia.org/wiki/Dental_fillings

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